Dual-Site Engineering of La/Ti Co-Doped BiFeO3 for Enhanced Visible-Light Photocatalytic Degradation: Synergistic Effects and High Stability

To address the persistent challenges of wide band gap (2.13   eV), high carrier recombination rates, and poor cycling stability in bismuth ferrite (BiFeO 3 BFO)-based photocatalysts, this study introduces an unprecedented La³⁺/Ti⁴⁺ dual-site doping strategy. La/Ti co-doped BFO nanoparticles (n% BLFTO) were synthesized using a sol-gel method. The synergistic effects of La³⁺-induced gradient oxygen vacancies (increased by 270%) and Ti³⁺/Ti⁴⁺ redox couples led to a significant band gap narrowing to 1.79   eV, extending visible light absorption to 450-700   nm. Remarkably, the optimized 30% BLFTO sample achieved a 98.9% degradation efficiency of Rhodamine B (Rh B) within 120 minutes-7.17% higher than pure BFO and maintained 95.92% efficiency after 12 cycles (2.98% decay), demonstrating exceptional stability rarely reported in prior works. In-situ X-ray Photoelectron Spectroscopy and Photoluminescence Spectroscopy analyses revealed that dual-doping synergistically modulates carrier dynamics via Fe²⁺/Fe³⁺ mixed valency and abundant oxygen vacancies, thereby prolonging carrier lifetimes and enhancing photocatalytic activity. This work pioneers a dual-doping framework that simultaneously enables highly efficient visible-light-driven degradation of Rh B and exceptional cycling stability, offering new insights for the design of robust photocatalysts for environmental remediation and renewable energy applications.